Generally, a reverse transcriptase has an activity of synthesizing cDNA with the use of RNA as a template (hereinafter, referred to as “RNA dependent DNA polymerase activity”), an activity of synthesizing DNA with the use of DNA as a template (hereinafter, referred to as “DNA dependent DNA polymerase activity”), and an activity of degrading RNA strand in RNA:DNA hybrid (hereinafter, referred to as “RNase H activity”).
The reverse transcriptase has been used in application including analysis of nucleotide sequence of mRNA which reflects an amino acid sequence of a protein expressed in a living body, construction of cDNA library, RT-PCR, and the like, since the reverse transcriptase has the RNA dependent DNA polymerase activity. Conventionally, Moloney murine leukaemia virus reverse transcriptase or avian myeloblastosis virus reverse transcriptase has been used for the application.
In addition, when mRNA has a nucleotide sequence likely to form secondary structure, cDNA synthesis by the reverse transcriptase is inhibited by the secondary structure. Therefore, it is desired that cDNA is synthesized while inhibiting formation of the secondary structure by elevating reaction temperature. However, since the Moloney murine leukaemia virus reverse transcriptase and the avian myeloblastosis virus reverse transcriptase have low thermal stability, the Moloney murine leukaemia virus reverse transcriptase and the avian myeloblastosis virus reverse transcriptase are sometimes inactivated at a temperature capable of inhibiting the formation of secondary structure of RNA. Therefore, a reverse transcriptase possessing improved thermal stability is proposed (for instance, see Patent Literature 1 and Non Patent Literature 1).